This invention generally relates to reclosable bags whose interior volume is hermetically sealed when the bag is closed. In particular, the invention relates to, but is not limited to, evacuable reclosable storage containers or other evacuable reclosable containers.
Collapsible, evacuable storage containers typically include a flexible, airtight bag, an opening through which an article is inserted inside the bag, a zipper for closing the opening and hermetically sealing the bag, and a fixture through which excess air is evacuated from the bag. A user places an article into the bag through the opening, seals the opening, and then evacuates the air in the bag through the fixture. With the bag thus evacuated, a compressible article contained therein may be significantly compressed so that it is easier to transport and requires substantially less storage space.
Collapsible, evacuable storage containers are beneficial for reasons in addition to those associated with compression of the stored article. For example, removal of the air from the storage container inhibits the growth of destructive organisms, such as moths, silverfish, and bacteria, which require oxygen to survive and propagate. Moreover, such containers, being impervious to moisture, inhibit the growth of mildew.
Not only large, compressible items such as clothing may be stored in a collapsible, evacuable storage container. For example, it may be desirable to store bulk items made of small particles, such as powders or granulated resins, in an evacuated container. One situation that commonly occurs is that a particular bulk item is shipped in a large, rigid container such as a drum. Bulk items may be moisture sensitive and are sealed against moisture during shipment. But many times a user does not need to use the entire contents of the large container, and so once exposed to air the remaining bulk contents quickly become unusable and are thus wasted.
One collapsible, reusable, evacuable storage container is shown in U.S. Pat. No. 5,480,030. This patent discloses a bag that is reclosable by means of a plastic zipper and that is evacuable via a one-way air valve assembly having a flexible diaphragm that seals against a valve seat. The valve assembly also has vanes positioned to prevent the bag material or bag contents from obstructing air holes or the diaphragm while air is being evacuated through the valve assembly.
In many reclosable bags, the zipper comprises a pair of mutually interlockable zipper strips, each zipper strip having a respective generally constant profile along the interlockable portion of the zipper. The ends of the zipper strips are joined together at the sides of the bag. For example, it is known to fuse the ends of the zipper strips together, at the same time that the bag side seals are formed, by the application of heat and pressure. This “thermal crushing” of the plastic zipper creates a transition between “as is” zipper and crushed zipper that is susceptible to the presence of leaks through which air can enter an evacuated bag.
Another known problem afflicting evacuable storage containers is that consumers can inadvertently open an evacuable storage container too wide, so that the open zippered “mouth” of the bag is subjected to much stress where the zipper strips meet and are joined together. If the storage container is opened too wide (over-opened), the zipper joint (where the zipper strips come together) can be stressed and damaged, leading to leaks when the bag is later closed and evacuated.
There is a continuing need for improvements in the construction of storage containers that need to be hermetically sealed. In particular, there is a need for an improved evacuable storage container wherein leakage is eliminated in the areas where the bag side seals overlap the ends of the zipper. There is also a need for a construction that distributes stresses and loads away from the zipper profiles when the mouth of the bag is over-opened, thereby preventing leaks induced by over-opening.